[0001] The present invention relates to an instrument for taking a tissue sample.
[0002] More specifically it concerns an instrument of the type described in
WO 02/065919, in which a spiral or helical tissue receiving element is turned in the tissue from
which a sample must be taken, after which the tissue around this tissue receiving
element is cut with a sharp cannula around the tissue receiving element and is torn
off at the distal end of the tissue receiving element, thereby obtaining a tissue
sample in the tissue receiving element.
[0003] However, this known instrument has a number of disadvantages. They are related to
the fibres in the various tissues.
[0004] The organs in human and animal bodies have fibres of connective tissue. They give
structure to the organ, which normally speaking additionally consist of soft, unstructured
tissue. These fibres in organs can run in relatively arbitrary directions or can have
one or more primary directions.
[0005] It has turned out that, when the tissue to be sampled has 'unifrontal' fibres that
enter the cut tissue via the frontal connection of the sample to the rest of the tissue,
thus where the tissue has to tear loose, and similar fibres that make a curve in order
to recede in the same direction, also via this frontal connection, the 'bifrontal'
fibres, it can happen that the force exerted by the known spiral or helical tissue
receiving element is not great enough to tear off these fibres.
[0006] As a result it may happen that during the biopsy, the intended tissue sample, that
is in the tissue receiving element, is not torn loose from the other tissue and isolated
as a sample, but instead of this, while the tissue receiving element is withdrawn
from the tissue, the intended sample remains attached to the organ and thus slides
out of the receiving space.
[0007] When unifrontal fibres are present, but even more so with the presence of lateral
fibres, which extend partly transverse to the longitudinal direction of the tissue
receiving element and thus protrude through the space between the windings of the
spiral or helical tissue receiving element, there is also the disadvantage that the
sharp cannula partially pushes the fibres along during the cutting movement, instead
of cutting through them, and that these fibres accumulate in the very limited space
between the tissue receiving element and the cannula, and thereby impede the movement
of the cannula or even make it impossible.
[0008] This results in the tissue samples not being cut well, if at all.
[0009] Certainly when taking samples from relatively hard tissues, the spiral or helical
tissue receiving element can also expand due to the forces acting on it, such that
the desired movement of the cannula is hampered or rendered impossible.
[0010] It is known, for example in
US 6083237, to narrow the point, thus the distal end, over a short length, i.e. a maximum of
one winding of such a spiral, in order to enable easier penetration into the tissue.
[0011] This has the disadvantage that this narrowed point, during insertion, damages the
tissue that will later serve as a sample, so that taking an undamaged sample of a
certain size is difficult.
[0012] The purpose of the present invention is to provide a solution to at least one of
the aforementioned and other disadvantages, by providing an instrument for taking
a tissue sample, that comprises a tissue receiving element with a distal end and a
proximal end and at least partly consists of a spiral or helix that has an outer surface
and which has a central longitudinal axis, whereby the spiral or helix has at least
has one zone where the distance from the outer surface to the central longitudinal
axis is smaller than at a more proximally located part of the spiral or helix, whereby
the zone runs from the distal end in the direction of the proximal end over a distance
of at least one complete winding of the spiral or helix.
[0013] This means that the zone at least partly extends in the region of the spiral or helix
that is intended to be surrounded by the cannula during a sampling procedure, and
to exert a cutting effect together with this cannula during this procedure.
[0014] This has the advantage that there is space for unifrontal fibres in the tissue to
protrude outside the tissue receiving element, even after the cutting by a cannula,
such that the pulling force exerted by the physician on the instrument can be more
effectively transmitted to the tissue, so that the tissue tears off, as desired. This
effect is of course much greater with bifrontal fibres, which can be located around
the windings of the tissue receiving element, and on which a much greater force can
thus be exerted.
[0015] This means that the risk of the instrument being extracted from the tissue without
a significant sample being taken is reduced.
[0016] As a result, on the part where the distance from the outer surface to the central
longitudinal axis is smaller, there is space for the fibres that have not been cut
through to accumulate, such that the cutting movement is impeded less or not at all.
[0017] This configuration of the tissue receiving element also provides space to accommodate
any expansion of the tissue receiving element without disturbing the cutting movement.
[0018] It is self-evident that these effects are greater as the zone, over which the distance
from the outer surface to the central longitudinal axis is smaller than at a more
proximal part of the spiral or helix, extends over a greater proportion of the tissue
receiving element, and at least extends to the section of the spiral or helix that
is intended to have a cutting effect together with the cannula, thus the section over
which the cannula slides during normal usage.
[0019] In a preferred embodiment that is why the said zone runs from the distal end in the
direction of the proximal end over a distance that corresponds to at least two full
windings, more preferably over at least half of the length of the spiral or helix,
or even over the entire length of the spiral or helix.
[0020] In a preferred embodiment, along an intersecting line between the outer surface and
a plane of which the central longitudinal axis forms part, where this intersecting
line runs through the zone, at every position, the distance from the outer surface
to the central longitudinal axis is less than or equal to the distance from the outer
surface to the central longitudinal axis at every more proximal position along the
intersecting line. More preferably the distance from the outer surface to the central
longitudinal axis is less than the distance from the outer surface to the central
longitudinal axis at every more proximal position along the intersecting line.
[0021] In a further preferred embodiment the distance from the outer surface to the central
longitudinal axis at the distal end is smaller than at the proximal end, viewed along
the intersecting line of the outer surface with every plane of which the central longitudinal
axis forms part.
[0022] In another further preferred embodiment the spiral or helix has an inner surface,
whereby that inner surface, viewed from the distal end, defines the shape of a geometrical
cylinder. This means that the inside space has a constant diameter over a certain
distance from the distal end, or even over the entire length of the spiral, and thus
does not narrow near the point.
[0023] This means that the thickness of the body that forms the spiral or helix is smaller
near the distal end than near the proximal end.
[0024] In this way sufficient space remains centrally in the tissue receiving element to
take an undamaged sample of the desired size.
[0025] This also prevents the action of inserting the spiral leading to damage of the tissue
that is taken as a sample.
[0026] In a further preferred embodiment the instrument also comprises a tubular cutting
element that has a distal end with a cutting edge and which fits around the tissue
receiving element. This cutting edge can take on different forms, such as flat, toothed,
etc.
[0027] With the intention of better showing the characteristics of the invention, a preferred
embodiment of an instrument according to the invention is described hereinafter by
way of an example, without any limiting nature, with reference to the accompanying
drawings, wherein:
Figure 1 schematically shows a perspective view of an instrument according to the
invention;
figure 2 shows a cross-section of the instrument of figure 1 along the line II-II;
figures 3 to 5 show the instrument of figure 2 during use in three different tissue
types;
figures 6 and 7 each show an alternative embodiment of the instrument according to
the invention, in a cross-section as in figure 2;
and figures 8 to 10 together show an alternative embodiment of the instrument according
to the invention, whereby in figure 8 this is a cross-section as in figure 2, and
in figures 9 and 10 cross-sections perpendicular thereto.
[0028] The instrument 1 shown in figures 1 to 5 comprises a tubular cutting element 2 and
a tissue receiving element 3. The cutting element has a distal end 4 that has a sharp
edge 5 suitable for cutting. The cutting element has an inside diameter d
s.
[0029] The tissue receiving element 3 is formed by a helically extending metal body 6 with
a distal end 7 that is provided with a point that can penetrate the tissue and a proximal
end 8.
[0030] In this case the helical body has six windings 9. The helix has a central longitudinal
axis X-X', an inner surface 10 and an outer surface 11.
[0031] The inner surface 10 is hereby the surface of the helical body 6 that is turned towards
the central longitudinal axis X-X'. The outer surface 11 is hereby the surface of
the helical body 6 that is turned away from the central longitudinal axis X-X'.
[0032] The inner surface 10 has such a shape that it defines a cylindrical tissue receiving
space 12 with a diameter d
w.
[0033] The outer surface 11 is such that for every successive winding 9, from proximal to
distal, the distance from the outer surface 11 to the central longitudinal axis X-X'
is smaller, in other words the thickness of the helical body 6 is smaller for each
successive winding 9.
[0034] In this embodiment, but not necessarily, this is the case around the entire periphery
of the helix, thus along the intersecting line of the outer surface 11 with every
plane of which the central longitudinal axis X-X' forms part.
[0035] Thus for the most distal winding 9, as is clear from figure 2, the outer surface
11 is located at a distance of 0.5 * d
d from the central longitudinal axis X-X', while it is a distance of 0.5 * d
p for the most proximal winding.
[0036] The tissue receiving element 3 is connected by means of a shaft 13 to a handle (not
shown) in order to give a movement to the shaft 13 and thereby to the tissue receiving
element 3.
[0037] The cutting element 2 can be made, for example, by taking a first tube, for example
of metal, for example with an inside diameter of d
s of 2 mm and providing it with a sharp edge 5.
[0038] The tissue receiving element 3 can be made for example by taking a second tube, for
example of metal, with an outer diameter d
p that is just less than the inside diameter d
s of the first tube, and providing this second tube with a helical cut by means of
a milling cutter for example, so that a metal helix remains.
[0039] In this example the tube and the rod are both made of metal, but they can also be
made of different materials.
[0040] The difference between the outer diameter d
p of the second tube and the inside diameter d
s of the first tube is determined experimentally, because the combination of the tissue
receiving element 3 and the cutting element 2 partly determine the cutting properties
of the instrument 1 to be formed.
[0041] Then the windings 9 of the helix, going from one end, that will later become the
proximal end 8, to the other end, which will later become the distal end 7, are ground
away more per winding, so that a shape such as in figures 1 to 5 is formed.
[0042] Then the tissue receiving element 3 thus formed is provided with a shaft 13 and the
tissue receiving element 3 and the cutting element 2 are put together into the instrument
1.
[0043] An embodiment in which the shaft 13 is formed by a part of the second tube that is
not provided with a helical cut is also possible.
[0044] The operation of the instrument according to the invention is simple and as follows.
[0045] First a localisation needle, a 'trocar' is inserted at the site where a tissue sample
must be taken. Then the cutting element 2, the size that is adapted to the localisation
needle, is slid over the localisation needle, also to the site where the tissue sample
must be taken. The localisation needle is now withdrawn.
[0046] Then the tissue receiving element 3 is brought through the cutting element 2. Through
a turning movement this tissue receiving element 3 is now turned in the tissue from
which a sample must be taken. The tissue in the tissue receiving space 12 is thus
not disturbed. This is the situation as shown in figures 3, 4 and 5.
[0047] Then the cutting element 2 is slid in the distal direction P, whereby a rotation
movement is made at the same time. Also through the interaction between the tissue
receiving element 3 and the cutting element 2 the tissue is now cut loose around the
tissue receiving element 3, as indicated in the drawings by line S.
[0048] Hereby there is some space between the cutting element 2 and the outer surface 11,
primarily near the distal end 7.
[0049] During cutting this space provides room for the parts of the unifrontal fibres 14,
of which a part protrudes laterally outside the tissue receiving element 3, as shown
in figure 3, or for the lateral fibres 15 that protrude outside the tissue receiving
element 3, as shown in figure 4. As a result the cutting action is not disturbed or
only to a limited extent.
[0050] Then a pulling force is exerted on the instrument 1 or receiving element 2 in the
proximal direction Q. As a result the tissue sample tears away near the distal end
7 of the tissue receiving element 3, according to the tear line 16, and it can be
taken outside the body of the patient for the necessary analyses.
[0051] Hereby the space between the outer surface 11 and the cut S is important, because
this enables parts of the bifrontal fibres 17, after cutting, to protrude outside
the tissue receiving element 3 without being cut off, so that a significant force
can be exerted on the tissue sample by the physician, via the tissue receiving element
3, resulting in the tissue sample tearing away, and with little risk of sample loss
when the tissue receiving element 3 is pulled entirely out of the tissue.
[0052] As shown in figure 5, thanks to the space between the outer surface 11 and the cut
S, the bifrontal fibres 17 can flow back in a curve around the helical body 6, so
that via these bifrontal fibres 17 a very large force can certainly be transmitted
from the tissue receiving element 3 to the tissue.
[0053] The alternative instrument 1 of figure 6 differs from that of figure 2, because the
outer surface 11 of each winding is not parallel to the central longitudinal axis
X-X', but follows a straight line between the most distal winding 9 and the most proximal
winding 9.
[0054] The alternative instrument 1 of figure 7 differs from that of figure 2 because the
most distal windings 9 each have an outer surface 11 with a short distance 0.5 * d
d to the central longitudinal axis X-X', which is the same for each of these windings.
The most proximal windings also all have the same larger distance 0.5 * dp to the
central longitudinal axis X-X'.
[0055] The cross-section of the helical body 6 transverse to the direction in which the
body extends helically, is also parallelogram-shaped, whereby the proximal and outermost
angle α is acute.
[0056] The alternative instrument of figures 8 to 10 differs from the instruments 1 described
earlier because the outer surface 11 of the tissue receiving element 3 only has a
shorter distance to the central longitudinal axis X-X' than at the proximal end 8
over two zones extending parallel to the longitudinal axis X-X' at the distal end
7.
[0057] Outside these zones the entire outer surface 11, viewed over all windings 9 from
distal to proximal, is straight over the entire length of the helical body 6, i.e.
parallel to the central longitudinal axis X-X'.
[0058] The form of the outer surface 11 of the tissue receiving element 3, going from proximal
to distal, in the above examples is shown as a linear or step function. However, other
forms are also possible such as hyperbolic or parabolic, or combinations thereof.
[0059] It should be noted that in the drawings described above the differences in the diameters
d
p and d
d are enlarged, for the purpose of better clarifying the invention. In a practical
instrument, with a diameter d
p of approximately 3 mm, the difference between d
p and d
s is approximately 10% of d
p, thus approximately 0.3 mm.
[0060] The present invention is by no means limited to the embodiments described as an example
and shown in the drawings, but an instrument according to the invention can be realised
in all kinds of variants, without departing from the scope of the invention.
1. Instrument (1) for taking a tissue sample, that comprises a tissue receiving element
(3) with a distal end (7) and a proximal end (8) and at least partly consists of a
spiral or helix that has an outer surface (11) and which has a central longitudinal
axis (X-X'), characterised in that the spiral or helix has at least has one zone where the distance (dd) from the outer surface (11) to the central longitudinal axis (X-X') is smaller than
at a more proximally located part of the spiral or helix, whereby the zone runs from
the distal end (7) in the direction of the proximal end (8) over a distance of at
least one complete winding (9) of the spiral or helix.
2. Instrument (1) according to claim 1, characterised in that the zone runs from the distal end (7) in the direction of the proximal end (8) over
a distance of at least two complete windings (9) of the spiral or helix.
3. Instrument (1) according to any one of the previous claims, characterised in that along an intersecting line of the outer surface (11) and a plane of which the central
longitudinal axis (X-X') forms a part, and this intersecting line runs through the
zone, at every position the distance from the outer surface (11) to the central longitudinal
axis (X-X') is less than or equal to the distance from the outer surface (11) to the
central longitudinal axis (X-X') at every more proximal position along the intersecting
line.
4. Instrument (1) according to any one of the previous claims, characterised in that the distance (dd) from the outer surface (11) to the central longitudinal axis (X-X') at the distal
end (7) is smaller than at the proximal end (8), viewed along the intersecting line
of the outer surface (11) with every plane of which the central longitudinal axis
(X-X') forms part.
5. Instrument (1) according to any one of the previous claims, characterised in that the spiral or helix has an inner surface (10) whereby the distance (dw) from this inner surface (10) to the central longitudinal axis (X-X'), over at least
a section of the zone that connects to the distal end (7), at every position is equal
to this distance (dw) at every more distally located part of the spiral or helix.
6. Instrument (1) according to claim 5, characterised in that the distance (dw) from the inner surface (10) to the central longitudinal axis (X-X'), at every position
in the zone is equal to this distance (dw) at every more distally located part of the spiral or helix.
7. Instrument (1) according to any one of the previous claims, characterised in that the spiral or helix has an inner surface (10) that defines the shape of a geometrical
cylinder.
8. Instrument (1) according to any one of the previous claims, characterised in that the spiral or helix is formed by a helical body (6) whereby the thickness (dd-dw) of the helical body (6) for every successive winding (9), going from the proximal
end (8) to the distal end (7), is smaller than for the previous windings (9).
9. Instrument (1) according to any one of the previous claims, characterised in that the cross-section of the tissue receiving element (3) transverse to the direction
in which the spiral or helix extends spirally or helically, has such a shape that
the most proximal and outermost angle (α) of this cross-section is acute.
10. Instrument (1) according to claim 9, characterised in that the cross-section has the form of a parallelogram or triangle.
11. Instrument (1) according to any one of the previous claims, characterised in that it also comprises a tubular cutting element (2) that has a distal end (4) with a
sharp edge (5), and which fits around the tissue receiving element (3).
12. Instrument (1) according to claim 11, characterised in that the cutting element (2) fits closely around the tissue receiving element (3) and
can slide.
13. Instrument (1) according to claim 12, characterised in that the cutting element (2) fits around the tissue receiving element (3) rotatably and
can slide in the longitudinal direction.
14. Instrument (1) according to claim 12 or 13, characterised in that the cutting element (2) and the tissue receiving element (3) are of such a shape
and size that during use they work together and have a cutting effect on tissue that
surrounds the spiral or helix.